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Updated! Firefly 589nm DL Review!

Sigurthr

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I'm curious about the total thermal impedance between the pertinent components in the module and the host housing. I wonder if an external clamp on Heatsink / heat exchanger could extend the duty cycle or improve subsequent use output levels.
 

BowtieGuy

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Awesome! Do you think you can do a metering with your ophir where you plot the output power against time while noting starting temperature? If there is no data export an anecdotal graph using 5sec intervals will suffice for me.

I noticed mine is very sensitive to temperature in terms of peak output; when the laser is under 70F I get peaks over 90mW and average of about 70mW for most of the 1min duty cycle, but if the laser is already over 70F the peak and average power drops drastically per degree F above 70F (at 80F it peaks at 61mW and averages 39mW, at 90F it peaks at 44mW and averages 20mW).
That sounds about right. That's about what my PGL-C does. The module gets really hot very quickly. When I was doing my alignments, I would have to hold the module Lily was adjusting crystals and it gets really hot within seconds of turning on.

I've noticed a similar sensitivity to temperature with my PGL-C 589. I've seen it peak near 160mW at start up, and average at 125 - 135mW for probably two minutes.
It then drops off significantly, and rapidly, once to as low as the mid 40mW range.
The first time I saw this happen, it scared the hell out of me; I thought it was permanently damaged!
I did notice that the host did not get warm to the touch during use. It wasn't until after a period of rest that any noticable warmth was felt; maybe the contact between the module and host isn't as good as it could be.
 

Sigurthr

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Yeah, it scared the hell out of me when mine hit 20mW too, lol. The website lists the duty cycle as "1 minute", with no cool down period specified. I typically give things a 1:5 use-to-cooldown duty cycle when there isn't good documentation, but 5min doesn't appear to be long enough to get back to "cold start" conditions, at least not during the summer time here. My host never gets warmer to the touch than about 86F during all my testing, but I'm not pushing the laser hard either. In typical usage I'll do a couple 10-15sec ON times which are followed by 15-30sec OFF times, and then I'll turn it on until visually the output is half as bright (roughly 1/4 the power ~20mW), and then put it away until next time.

I'm rather curious about pre-cooling the unit to say 55F or so and seeing how it responds, but I am concerned about condensation given the exposed front end optics.

By the way, how the hell are you supposed to remove the front "cap" (not the aperture plug) so you can attach a beam expander? I don't want to be rough with mine, but it certainly isn't hand tightened on there!
 

Sigurthr

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I may have to buy one (or two) of those rubber strap wrenches to try and get it off. No way in hell am I going to use any standard tool on this laser.
 
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I may have to buy one (or two) of those rubber strap wrenches to try and get it off. No way in hell am I going to use any standard tool on this laser.
I very carefully use a hammer and propane torch to remove mine. It's all in the wrist, takes some practice. It may take you a few tries but I'm confident you'll master it if your diligent.
 
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Seriously though, even though the host is clean and sleek for a DPSS of this output I'm not thrilled about it's heat sinking and duty cycle. I don't usually run mine for any more than 30-45 seconds but it just makes me a little bit nervous how quickly these warm up and how little sinking they have. These things are probably what 3% efficient in the conversion of 808nm to 589nm? I think it's in that ballpark. If that's so then it would take about 3w of pump power which is a boatload for a tiny little host like this. I would really love to transplant this puppy's guts into a solid copper host with some mass around the pump sink. Or even a well finned and significantly sized aluminum host would do well too. If it can't be easily opened I was even thinking of having one of our turners here cut the battery holder part of the host off, turn the remaining head down enough to get an even and smooth finish, and slide the remaining business end of this laser into a perfectly fitted host made from copper. I would think that as long as the thing isn't banged around on, the speeds needed to do this on a lathe shouldn't cause any issues with the internals on one of these. You could conceivably roll this laser across a table at speeds faster than needed to turn this down I would think. Maybe one of the lathe masters around here could comment.
 

IsaacT

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If you do this let me know how it goes. I have a bit of an obsession with making custom DPSS builds like that. This is tempting.
 
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Shakenawake

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3% huh, I thought it was worse. I was thinking the pump must be very powerful as well. these are small hosts, relatively speaking, not much bigger than a 501B. seems kinda like putting one of those new 3.5W 445nm diodes in a 501B, not something that would result in a high duty cycle. I think I'll manage, but will keep an eye on what you do with yours.

used to have a 1W+ 445nm spartan, I managed to remove the front end pretty easily. if yours is on there good, use patient, careful dillegence to remove it. maybe try something rubber to help grip it. like wrap it in a rubber band or use one of those oil filter wrench/jar opener things.
 

Sigurthr

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If you do manage to extract the module or modify the host, I'd love to see how it turns out.

I'm considering doing a tailcap current measurement to get a ballpark pump power level. Now, assuming it is TEC cooled (which would explain the fast heat up and rapid battery drain) we can assume an optimal balance of 50% power between TEC and pump. If it isn't actually TEC cooled, and Adam misspoke, then the conclusion would be that pump heatsinking is vastly inadequate or the conversion efficiency is much lower thus requiring perhaps even a 5W pump.
 

trencheel303

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According to Wikipedia 589s are 3% efficient but that's probably an average or even conservative figure. I recall seeing eytyxhs meter his Rigel at over 10mW (the one that I now own) and ultimatekaiser has said these use 500mW pump diodes. That's 2-3% efficiency right there, although I understand I got a bit of a freak performer.

Given how much more powerful handheld 589s are than 593.5s (the CNI 2-20mW PGL-III-C is the most powerful handheld 593.5 I've seen) a good one is surely at least 3-5% efficient. If it was purely a matter of pump power, we'd at least see slightly brighter 593.5s, albeit at high cost. The supposed 3-5% efficiency would place the current DL 589 pump diodes at anything in the range of 1-2W, which seems far more realistic than 5W which is a rated efficiency of only ~1% given these are 50mW rated with higher peaks.
 
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ultimatekaiser

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I haven't metered my diode, but I thought they're generally 2.5-3.3W so that sounds about right. 588.6 isn't very efficient at all, 593.5 is a bit better, but much more temperature sensitive, which is why they tend to be lower power, But they are easier to produce. So it's kind of a catch 22.
 

trencheel303

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593.5 more efficient than 589, really?

To be honest I thought the opposite to all of that was true.

I always thought the 1342nm line was far pickier than the 1319, and is this not evidenced in 671s which can also be fickle? 589s are also supposed to be the newer better DPSS yellows as they were better in almost every way than 593.5. Power, stability etc.

Bit confused now...
 
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ultimatekaiser

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Yeah the 1342 line is a bit bigger, but a bit more sensitive, and it likes to compete with 1064, so when you amplify both, odd stuff happens...where in a 671 this isn't a problem, since you are rejecting the 1064 line.
 
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trencheel303

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Right ok, guess that clears that up a bit then. I'm guessing it's extremely rare in 589s then to see any green output? I quite like that about 593.5, and it happens quite predictably under set conditions in mine.
 




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